Mimar Hayrüddin was a royal Ottoman architect. His birth and death dates are unknown, but we do know that he served as chief architect under Ottoman sultan Bayezid II (r. 1481-1512/886-918 AH) and that his father, called Ustad Murad, was also an architect. Among his works are the complexes (külliye) of Bayezid II at Amasya and Edirne, as well as several other regional mosques, a number of stone bridges, and repairs to the fortifications around Istanbul and the Bosphorus.

His architectural complexes are distinguished by their massing of architectural components such as domes, porticoes, and minarets to create monumental and harmonious forms. The plans of both the Amasya and Edirne külliyes are centered on large domed boxes inspired by Byzantine imperial church architecture but taken in new directions to accommodate Muslim ritual. The fascination with large and bright domed prayer halls already evident in Amasya and Edirne would be adopted by his successors, including Mimar Sinan who codified Ottoman imperial architectural style. Hayrüddin is thus considered to be one of the founders of the classical Ottoman style that flourished in the sixteenth century/tenth century AH.

Sources:

Aslanapa, O. “ustād K̲h̲ayr al-Dīn.” Encyclopedia of Islam, Second Edition, 2012. http://dx.doi.org/10.1163/1573-3912_islam_SIM_4259.

Bloom, Jonathan M. and Sheila S. Blair, ed. "Hayreddin." The Grove Encyclopedia of Islamic Art and Architecture. Oxford University Press, 2009. http://www.oxfordreference.com/view/10.1093/acref/9780195309911.001.0001/acref-9780195309911-e-386

Goodwin, Godfrey. A History of Ottoman Architecture, 134 ff. London: Thames and Hudson, 1971.